Soft ceramic kitchenware internally coated with a non-stick resin and the method to achieve this

Claim 2

Soft ceramic kitchenware internally coated with a non-stick resin and having an intermediate bonding layer, wherein the said bonding layer is made of a lead-free frit for ceramic with a melting point lying between 500 and 950°C and includes: a) a glaze that melts essentially at such temperatures and which penetrates and anchors in the pores of the ceramic biscuit, eliminating part of the air, and b) a quantity of less than 50% by weight of at least one substance which essentially does not melt at the melting temperature of the glaze and which solidifies immediately at a slight temperature drop and which forms a diffused granulation surface of the glaze with hard grains, enclosed in the melt part and anchored to the biscuit base.

Claim 3

Kitchenware according to claim 1, in which the substance that essentially does not melt at the melting temperature of the glaze may be chosen among cryolite, alumina , silica, quartz, kaolin, petalite, zirconia, or their mixtures.

Claim 4

Kitchenware, according to claim 2, where the substance which essentially does not melt at the melting temperature of the glaze is a mixture of clay and quartz containing approximately 7,5% by weight of silica.

Claim 5

Kitchenware, according to any one of the previous claims, where the lead-free frit is made of a glaze that melts at approximately 950 0 C and of pulverised quartz.

Claim 6

Kitchenware, according to any one of the previous claims, where the non-stick resin is polytetrafluoro ethylene.

Claim 7

Procedure for the manufacture of the soft ceramic kitchenware internally coated with a non-stick resin, according to claim 1, wherein it includes: - coating of the internal surface of the ceramic biscuit with an acqueous dispersion of a lead-free frit for ceramics having a melting point lying between 500 and 950° C and made up of a glaze which melts essentially at these temperatures and of at least one substance that essentially does not melt at the melting temperature of the glaze, or which solidifies immediately at a slight temperature drop; - drying of the coated biscuit and firing of the said biscuit at a temperature lying between 500 and 950°C, so that the glaze melts, penetrates and forms a bond inside the biscuit pores and the unmelted part forms a diffused granulation over the surface with hard grains, enclosed in the melted part and anchored to the base of the ceramic biscuit; - application over the rough surface of one, or more layers of non-stick and hydrophobic resin, and - firing of the coated kitchenware by treatment in an oven at a temperature lying between 350 and 450 0 C.

Claim 8

Procedure, according to claim 6, where the dispersion of the frit is applied in a 10 - 15 microns layer

Claim 9

Procedure, according to claim 6, where the thickness of the non-stick resin layer is a minimum over the grain apexes and greater over the depressions.